I'm biased but I see no reason to not replace the front springs with a 5658, 5660, 5662 or 5664. I also see no reason to not put tall lower ball joints in because they help the geometry, lower the front of the car without reducing suspension travel, and your front lower balljoints are probably shot anyways and need replaced.
The 5658-64 series are OEM replacements for various 3rd gen F bodies and S10/Blazers. None of those vehicles are inherently rough riding.
Your ride height will vary but swapping from a 30-40yr old OEM spring to a new replacement, even if it's the exact replacement will probably lift the car because the old spring is sagged out. That's why going to the 5658-64 series and a tall lower ball joint helps, the chance of putting an uncut spring and getting the ride height you want is much better then putting in an OEM replacement PN#.
Plus, the 5658-64 series spring are much shorter, with a higher spring rate, than the OE G body ones so installing them is a much less scary venture. The OE springs will shoot out like a rocket when you drop the lower ball joint but a 5658-64 spring will fall in if you have to cut 1/2 coil or should be able to be pried in without a spring compressor.
